package java1224;

public class Java01 extends Object {

    public static void main(String[] args) {

        // 变量和常量

        // 变量：可以变化、可以更改
        int a = 2;
        System.out.println(a);
        a = 3;
        a = 5;
        a = 7;
        System.out.println(a);

        // 常量：不能更改、用final关键字修饰
        final int b = 6;
//        b = 5;

        // 数字下划线
        int salary = 1_000_000_000;
        double d = 3.141592_65358_979;
        System.out.println(d);
        System.out.println(salary);

        // 赋值

        int x = 3;
        double y = 3.0;
        x += y;

    }

}
